Northrop Grumman announced in 2010 that it would close Avondale, shifting operations to its Pascagoula, Miss., shipyard. It later spun off those and other shipyard operations as Huntington Ingalls, based in Newport News, Va.

Huntington Ingalls has been trying to transfer Avondale to someone who would redevelop it, but has found no takers. Most of the remaining 740 employees would be laid off this summer without a new user.